/Engine/Source/Runtime/Engine/Classes/GameFramework/MovementComponent.h
Returns true if the current velocity is exceeding the given max speed (usually the result ofGetMaxSpeed()), within a small error tolerance. Note that under normal circumstances updates cause by acceleration will not cause this to be true, however external forces or changes in the max speed limit can cause the max speed to be violated.
virtual bool IsExceedingMaxSpeed ( float MaxSpeed ) const